VAN 121: Veterinary Gross Anatomy-II (2+2)

CEREBELLUM

• The cerebellum or lesser brain is separated from the cerebral hemispheres by the great transverse fissure.
• It overlies the pons and greater part of the medulla oblongata and the fourth ventricle. It is globular in shape and compressed dorso-ventrally.
• The surface of the cerebellum is cut into gyri by narrow but deep sulci into which the piamater dips.
• The anterior surface faces dorsally and forwards and is covered by the tentorium cerebelli.
• The cerebellum is connected by three pairs of peduncles with the medulla, pons and midbrain. The cerebellar peduncles are three on each side; join the central white substance of the cerebellum called the corpus medullare at its base. The posterior peduncle is the restiform body of the medulla.
• The middle peduncle or brachium pontis is formed by the continuation of the lateral parts of the pons. The anterior peduncle or brachium conjunctivum passes forwards on either side on the dorsal face of the pons forming the lateral boundaries of the fourth ventricle.
• These two peduncles disappear under the corpora quadrigemina into mid brain.  
• The cerebellum is divided into three lobes, a median vermis and two lateral hemispheres.
• The vermis is curved in a circular manner so that its two extremities are close together or even in contact with each other on the ventral face.
• The anterior extremity gives attachment to the anterior medullary velum or valve of Vieussens. Similarly another thin lamina, which connects the posterior extremity to the medulla oblongata called the posterior medullary velum.

• The hemispheres are separated by two vela that form the roof of the fourth ventricle.
• The hemispheres are separated by two fissures from the vermis and present the flocculus ventrolaterally.
• On sagittal section, the cerebellum consists of gray cortex outside and white substance internally.
• The latter consists of a central mass, the corpus medullare that joined by the peduncles.
• Corpus medullare gives off primary branches to the lobules. From these, secondary and tertiary laminae arise and the entire arrangement is spoken as arbor vitae.
• The central gray substance consists of four groups of nerve cells which are embedded in the central white mater the nucleus dentatus, nucleus embolifomis, nucleus globosus and nucleus fastigii.
• The cerebellum is concerned with control of equilibrium and the synergistic control of skeletal muscles involved in complex movement. View the animation